Owing to their excellent weather resistance, chemical resistance and thermal stability, acrylate-styrene-acrylonitrile (ASA) thermoplastic resins have been used for exterior supplies including electric and electronic components, building materials, sporting goods, car parts, etc, and more specifically applied to satellite antennas, kayak paddles, chassis joiner and profile, door panel, car radiator grill, side mirror housing, etc.
Resins having poor weather resistance, for example acrylonitrile-butadiene-styrene (ABS) resin, are required to be processed by plating or painting to improve their weather resistance and polishing. But, the additional processes raise the price and environmental problems, which had better be avoided.
Unlike ABS resin, ASA resin has excellent weather resistance, making it very useful for external use, and is produced without surface coating, plating and painting processes. Besides, the omission of post-process results in the lowering of the production price and pro-environmental product. However, ASA resin is not resistant to scratch because plastic is exposed on the outside of surface and might have poor outward appearance because plating is omitted.
Those problems of scratch and poor exterior quality are possessed by most plastic products and numbers of methods have been proposed to overcome the problems.
U.S. Pat. No. 6,048,617 describes that the properties such as weather resistance, scratch resistance and thermal stability could be improved by surface coating with acrylic thermosetting coating agent on PC, PVC, ABS resin moldings. U.S. Pat. No. 6,605,656 B2 describes that scratch resistance could be improved by alloying olefin resin and nylon resin using compatabilizer.
U.S. Pat. No. 4,579,909 describes the method to improve the physical properties such as impact strength and bending strength by using trimix of ASA, PMMA and PC.
U.S. Pat. No. 5,068,285 describes that MBS, as an impact stiffener, was added to the blend of PC and ASA, resulted in the improvement of compatibility and elasticity. However, the addition of MBS also caused the decrease of weather resistance.
U.S. Pat. No. 6,476,126 B1 describes the use of the blend of ASA resin and PC resin, which was though limited in the dealing of exterior quality problem according to the ASA graft resin polymerization and in explanation of simple a blend resin composition not including any compatabilizer.
Therefore, more studies on a thermoplastic resin having excellent exterior properties are required.